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Yesterday, in Teva Pharmaceuticals USA, Inc., et al v. Sandoz, Inc. et al., (here) the U.S. Supreme Court reversed decades of CAFC precedent permitting de novoreview of district court patent claim constructions. More specifically, the high court explained that when reviewing a district court's resolution of subsidiary factual matters made in the course of its construction of a patent claim, the CAFC must apply a "clear error," not a de novo, standard of review. This decision will also impact the CAFC's previous practice of applying de novo review of Patent Trial & Appeal Board (PTAB) claim construction decisions....or will it?

Key to yesterday's holding is the distinction between intrinsic versus extrinsic evidence. That is, when the district court/PTAB reviews only evidence intrinsic to the patent, the judge's determination is solely a determination of law, and the CAFC will review that construction de novo. However, where the district court/PTAB needs to consult extrinsic evidence in order to understand, for example, the background science or the meaning of a term in the relevant art during the relevant time period, and where those subsidiary facts are in dispute, courts/PTAB will need to make subsidiary factual findings about the extrinsic evidence, such as expert reports/declarations.

While the PTAB will sometimes refer to dictionaries (extrinsic evidence) in supporting a plain meaning of a claim term, in most cases the broadest reasonable interpretation in light of the specification is based solely on the intrinsic record—especially for technical terminology. Thus, the vast majority of constructions coming out of the PTAB for Inter Partes Review (IPR) will very likely remain subject to de novo review at the CAFC. Perhaps less so for Covered Business Method (CBM) filings that employ more plain language claims (i.e., where dictionary support is often sought). While declarations on claim meaning are often submitted to the USPTO/PTAB, most often the agency identifies its own definition consistent with the specification rather than "picking a winner" between competing expert definitions.

For those claim terms amenable to interpretation via extrinsic evidence, one needs to consider whether or not the technical decision makers of the PTAB might provide the more favorable read for appeal purposes given the newly accorded deference to such findings. Conversely, given the lack of technical expertise in the district courts as compared to the PTAB, whethor or not the courts might resort to extrinsic evidence where the expert agency would not.

Finally, note that means-plus-function claims will necessarily invoke questions of fact (e.g., structural equivalence). Where competently drafted, such claims provide a mechanism for avoiding the full breadth of a broadest reasonable interpreation, and now, second guessing of structural equivalents on appeal. A strategic smattering of such claims across a portfolio serves as a helpful hedge for patentees in a post-grant challenge setting.

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